The present disclosure relates to a developing device and an image forming apparatus including the same.
Conventional image forming apparatuses employing an electrophotographic method, such as a printer and a copier, include a photoconductive drum for carrying an electrostatic latent image, a developing device for supplying toner to the photoconductive drum to develop the electrostatic latent image into a toner image, and a transfer device for transferring the toner image from the photoconductive drum onto a sheet.
The developing device includes a developing roller for supplying toner to the photoconductive drum. The developing roller includes a stationary magnet having a plurality of magnetic poles, and a sleeve rotatable around the magnet. In a two-component developing method, developer containing toner and magnetic carrier is carried on the sleeve of the developing roller. In such a developing roller, it is necessary to separate developer from the developing roller after the supply of toner to the photoconductive drum.
There are conventionally known techniques that use repelling magnetic fields produced by adjacent like poles to separate developer from a developing roller. There is also known a technique in which a pair of south poles and a pair of north poles are successively arranged in a circumferential direction in order to allow developer to pass over each pair of adjacent like poles on the developer roller.